It was, according to accounts filtering out of the White House, an extraordinary scene. Hank Paulson, the US treasury secretary and a man with a personal fortune estimated at $700m (£380m), had got down on one knee before the most powerful woman in Congress, Nancy Pelosi, and begged her to save his plan to rescue Wall Street.

The exchange - and those in the room said Paulson was only half joking - took place moments after a White House meeting that was supposed to endorse a $700bn bailout ended in acrimony.

At the White House on Thursday afternoon were George Bush, and the two men who stand to inherit America's economic mess: Barack Obama and John McCain, along with other congressional leaders. In the 40 minutes the Democratic and Republican leaders sat around a long table, prospects for a rescue package slid from optimism to near despair.

"This sucker could go down," Bush is said to have told the group - referring to the teetering US economy.

By late yesterday the fate of Paulson's plan remained unclear. One certainty emerged though from several days of drama and suspense: 10 hours before the start of last night's presidential debate McCain abandoned his threat of a boycott and flew to Mississippi to meet Obama.

How did it come to this? What happened to a deal that had been so close to fruition before the meeting at the White House? And what was McCain's role, saviour or saboteur? By yesterday afternoon, angry Democrats were accusing McCain of sabotaging the deal to further his own presidential campaign - and even some Republicans were inclined to agree. "Clearly, yesterday, his position on that discussion yesterday was one that stopped a deal from finalising," the Republican whip, Roy Blunt, told reporters.

Mike Huckabee, a former rival of McCain for the Republican nomination was also critical of his tactics, calling the threat to postpone the debate a mistake.

The intertwining of presidential politics and America's credit crisis began at 8.30am on Wednesday morning when Obama put in a call to McCain, proposing the two candidates suspend their rivalry to issue a joint statement on the bail-out.

By that point, it was becoming clear that Paulson's rescue package was playing far better on Wall Street than in the rest of the country. Republicans and Democrats balked at the huge sums to be marshalled by the effort to bail out corporate institutions at a time when voters were hurting.

It was also becoming evident to both sides that, with an election six weeks away, a bail-out could be politically toxic.

For McCain, the crisis had begun badly. Last week, as the markets were engulfed in uncertainty, he continued to repeat his signature statement: "The fundamentals of our economy are strong." As late as Tuesday, the Republican admitted in an NBC interview that he had not taken the time to read the bail-out plan.

But by Wednesday morning, it was impossible for McCain to ignore the economy and the damage it was doing to his campaign. After running in a dead heat against Obama for much of the summer, and with his hopes boosted by his selection of Sarah Palin as his running mate, McCain was confronted with a poll showing it could all slip away.

The ABC-Washington Post survey, for the first time, gave Obama a clear lead over McCain, with 52% to 43%. Voters, when asked which candidate they trusted to handle the economic crisis, gave Obama an even more commanding lead.

McCain needed to take decisive action. He also needed to make a calculation about where he stood on the Wall Street bail-out. Did he want to be seen as the saviour of an unpopular bail-out, or was there more mileage to be had elsewhere?

The Arizona senator waited about six hours to return Obama's call. When he did at about 2.30pm, he mentioned that he was thinking of proposing a delay in the debates.

Obama admitted later he thought McCain was just "mulling over the idea".

But within the hour, his opponent popped up in front of the TV cameras in New York to announce that the urgency of reaching a deal on the bail-out compelled him to suspend his campaign and return to Washington.

McCain also threatened to pull out of last night's debate.

The talk of missing one of the central moments of any election campaign, guaranteed McCain maximum attention. But what unfolded next did not live up to the Republican's claims that he was sacrificing his own political interests to try to nudge Congress towards a deal.

Despite his protestations of urgency - McCain cancelled an appearance on the David Letterman show - he found time for an interview on the CBS evening news. He also went ahead with a speech at Bill Clinton's Global Initiative (CGI) summit on Thursday morning.

"I'm an old navy pilot, and I know when a crisis calls for all hands on deck," McCain said during the speech to the CGI in New York. "With so much on the line, for America and the world, the debate that matters most right now is taking place in the Capitol - and I intend to join it."

Amid the dramatics, Obama's central argument that US voters should have the chance to judge where the candidates stood on the economy went overlooked.

"The times are too serious to put our campaign on hold, or to ignore the full range of issues that the next president will face," Obama told the CGI by satellite.

By the time McCain arrived in Washington on Thursday, he was still casting himself as the saviour of the bail-out package, even though Pelosi had been telling reporters for hours that the two sides were confident of sealing their agreement by the end of the day.

But the House leader should have noted McCain's first port of call - to the footsoldiers of a Republican rebellion. McCain dropped in on a meeting of House Republicans, who were putting together an alternative plan that called for further deregulation of Wall Street.

Those Republicans, led by John Boehner, the minority leader, urged McCain to consider a more freemarket-based proposal than the one that was on the table. McCain carried on to the White House, sitting at the opposite end of a long table from Obama.

Their behaviour at the meeting was a study in contrasts, according to press accounts. Obama, granted deference by his fellow Democrats, led off the debate.

Then Boehner made his move, throwing down a plan that differed wildly from the one under discussion. McCain, asked for his opinion, stayed silent - and that, according to those at the meeting, was taken by his fellow Republicans as a sign of his support for the Republican revolt.

Into that silence, Democrats read a political stunt, designed to allow McCain to cast himself as a populist crusader against Wall Street fat cats on the campaign trail.

Barney Frank, the Massachusetts Democrat who led the negotiations for the House, called McCain's behaviour part of a battle between Bush and his fellow Republicans. "I didn't think we were going to have to be the referee of an internal GOP [Republican] ideological war," he told CBS.

Obama's chief strategist, David Axelrod, came to a similar conclusion about McCain's role. "All that happened was the waters got roiled and we had some political theatre. That's not what we need right now," he told MSNBC.

But the Republican candidate was unfazed, turning around to accuse his critics of injecting unnecessary theatrics into the crisis talks. "Americans saw a familiar spectacle in Washington," his campaign said in a statement. "At a moment of crisis that threatened the economic security of American families, Washington played the blame game rather than work together."

The Republican is evidently looking beyond Washington for a very different reaction to his manoeuvring on the economy, and that verdict will not be known until November 4.